Janez Kovač

Jožef Stefan Institute | IJS · Department of Surface Engineering

The application of hydrogen flooding was recently shown to be a simple and effective approach for improved layer differentiation and interface determination during secondary ion mass spectrometry (SIMS) depth profiling of thin films, as well as an approach with potential in the field of quantitative SIMS analyses. To study the effects of hydrogen f...

The application of hydrogen flooding was recently shown to be a simple and effective approach towards improved layer differentiation and interface determination during SIMS depth profiling of thin films as well as an approach with a potential in the field of quantitative SIMS analyses. To further study the effects of hydrogen, the flooding of H2 mo...

Lead-free ferroelectric 0.5Ba(Ti 0.8 Zr 0.2 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) thin films on platinized silicon substrates are prepared by chemical solution deposition route. The solution chemistry involves ethylene glycol and ethanol as solvents for alkaline earth...

A Pd-Cu-Au/C nanocatalyst with a low content of Cu (8.2 at. %) and Au (4.4 at. %), and an average crystallite size of about 2 nm was synthesized by employing a one-pot two-steps borohydride reduction method in the presence of sodium citrate, characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy a...

Nowadays, bacteria resistance to many antibiotics is a huge problem, especially in clinics and other parts of the healthcare system. This critical health issue requires a dynamic approach to produce new types of antibacterial coatings to combat various pathogen microbes. In this research, we prepared a new type of carbon quantum dots based on phlor...

Reducing friction is a promising strategy to decrease material losses and energy consumption in industrial systems. However, in aqueous-lubricated steel contacts, the contact pressure rarely exceeds 50 MPa during super-low friction due to excessive wear. This work demonstrates that even in steel/steel contacts, by combining graphene quantum dots (G...

Electrochemical water-splitting is a promising green technology for the production of hydrogen. One of the bottlenecks, however, is the oxygen evolution half-reaction (OER), which could be overcome with the development of a suitable electrocatalyst. Recently, non-noble metal, high-entropy oxides (HEO) have been investigated as potential OER electro...

The present study introduces an advanced surface modification approach combining electrochemical anodization and non-thermal plasma treatment, tailored for biomedical applications on stainless steel grade 316L (SS316L) surfaces. Nanopores with various diameters (100–300 nm) were synthesized with electrochemical anodization, and samples were further...

The cost of treatment of antibiotic-resistant pathogens is on the level of tens of billions of dollars at the moment. It is of special interest to reduce or solve this problem using antimicrobial coatings, especially in hospitals or other healthcare facilities. The bacteria can transfer from medical staff or contaminated surfaces to patients. In th...

In the article Mnemonic Rutile-Rutile Interfaces Triggering Spontaneous Dissociation of Water (doi: 10.1002/adma.202308027), Vesna Ribić, Vanja Jordan, Aleksander Rečnik, and co-workers demonstrate that epitaxial rutile fibers grown in acidic conditions are capable of conveying their structurally encoded properties into a neutral medium when re-imm...

A visible light photodetector is developed using cobalt (Co)‐doped cadmium sulfide (CdS) thin films that exhibits outstanding characteristics with a photocurrent of 284 μA, responsivity of 13.2 A W⁻¹, an extraordinary external quantum efficiency (EQE) of 4550%, exceptional sensitivity (2.84 × 10⁶%), and a rapid response time of 0.6 ms. These remark...

Although silicon has been demonstrated to be one of the best photoelectrochemical (PEC) substrate materials thanks to its low cost, mature manufacturing technique, and high theoretical photovoltage and saturation current density [1] , the development of robust Si-based PEC device has remained an existing challenge due to the fact that it is very ea...

Fourier transform infrared spectroscopy (FTIR) is one of the most widely used vibrational diagnostic techniques to investigate gas-phase reactive oxygen and nitrogen species (RONS). However, the technique carries intrinsic challenges, particularly in relation to interfering peaks in the spectral data. This study explores the interfacial processes t...

Cardiovascular diseases are a pre-eminent global cause of mortality in the modern world. Typically, surgical intervention with implantable medical devices such as cardiovascular stents is deployed to reinstate unobstructed blood flow. Unfortunately, existing stent materials frequently induce restenosis and thrombosis, necessitating the development...

Water interaction with mineral surfaces is a complex living system decisive for any photocatalytic process. Resolving atomistic structure of mineral–water interfaces is thus crucial for understanding these processes. Fibrous rutile TiO 2 , grown hydrothermally on twinned rutile seeds under acidic conditions, was studied in terms of interface transl...

In this study, high-temperature tribological behavior of nanolayered TiAlN/TiSiN coating was evaluated against the Al2O3 counter-body using a pin-on-disk tribometer. The coating was deposited on the WC-Co substrate, in an industrial unbalanced magnetron sputtering system. Tribological tests were conducted at room temperature, 500, 600, 700, and 760...

Development of a robust photocathode using low-cost and high-performing materials, e.g., p-Si, to produce clean fuel hydrogen has remained challenging since the semiconductor substrate is easily susceptible to (photo)corrosion under photoelectrochemical (PEC) operational conditions. A protective layer over the substrate to simultaneously provide co...

This study reports on the successful conjugation of SARS-CoV-2 S1 spike protein fragments with gold nanoparticles (AuNPs) that were synthesised with Ultrasonic Spray Pyrolysis (USP). This method enables the continuous synthesis of AuNPs with a high degree of purity, round shapes, and the formation of a surface that allows various modifications. The...

In this study, MNPs were functionalized with pyrocatechol (CAT), pyrogallol (GAL), caffeic acid (CAF), and nitrodopamine (NDA) at pH 8 and pH 11. The functionalization of the MNPs was successful, except in the case of NDA at pH 11. The thermogravimetric analyses indicated that the surface concentration of the catechols was between 1.5 and 3.6 molec...

Aiming at speeding up the discovery and understanding of promising electrocatalysts, a novel experimental platform, i.e., the Nano Lab, is introduced. It is based on state-of-the-art physicochemical characterization and atomic-scale tracking of individual synthesis steps as well as subsequent electrochemical treatments targeting nanostructured comp...

Nowadays, it is a great challenge to develop new medicines for treating various infectious diseases. The treatment of these diseases is of utmost interest to further prevent the development of multi-drug resistance in different pathogens. Carbon quantum dots, as a new member of the carbon nanomaterials family, can potentially be used as a highly pr...

Scandium (Sc) is known to be one of the most effective alloying elements of aluminum alloys. The only drawback is its high price, but that could change quickly due to the promising results of recent research on its extraction. However, the data on how it affects anodic oxidation are very scarce. In this research, we analyzed how a micro-addition of...

A versatile approach to the production of cluster- and single atom-based thin-film electrode composites is presented. The developed TiO x N y -Ir catalyst was prepared from sputtered Ti-Ir alloy constituted of 0.8 ± 0.2 at % Ir in α-Ti solid solution. The Ti-Ir solid solution on the Ti metal foil substrate was anodically oxidized to form amorphous...

This work reports on the investigation of Eurofer-97 erosion behaviour when exposed to the deuterium plasma of the linear device GyM. The erosion dependence of Eurofer-97 on the deuterium ion fluence, Φ≤2.3×1025 m−2, and temperature of the samples, T = 600 K and 990 K, was addressed. A bias voltage of −200 V was applied to GyM sample holder during...

Carbon quantum dots (CQDs) are well known as a promising therapeutic agent due to their excellent pro-oxidant, antioxidant, antibacterial and anticancer properties under visible light irradiation. This material is easy to produce by several bottom-up or top-down methods. In this study, we used citric acid as starting precursor to synthesize aqueous...

Decreasing iridium loading in the electrocatalyst presents a crucial challenge in the implementation of proton exchange membrane (PEM) electrolyzers. In this respect, fine dispersion of Ir on electrically conductive ceramic supports is a promising strategy. However, the supporting material needs to meet the demanding requirements such as structural...

This systematic study deals with the influence of deep cryogenic treatment (DCT) on microstructure and surface properties of austenitic stainless steel AISI 304 L on different length scales and in the surface region. The study incorporates different analysis techniques, such as light microscopy, scanning electron microscopy (SEM), energy dispersive...

The present work reports on cationization characteristics of organic molecules in alkali metal environment. Samples of arginine and polyethylene glycol polymers with average masses of 600, 1000 and 1500 were mixed with sodium- and potassium trifluoroacetate of various concentrations, and analyzed through secondary ion mass spectrometry. Bombardment...

In our study, plasma surface modification was employed to tailor the surface properties of magnesium in terms of surface chemistry, topography, and wettability. For two sets of samples, the plasma treatment involved two steps using two different gases (hydrogen and oxygen), while one set of samples was treated with one step only using oxygen. X-ray...

The influence of H2 flooding on the development of surface roughness during time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling was studied to evaluate the different aspects of a H2 atmosphere in comparison to an ultrahigh vacuum (UHV) environment. Multilayer samples, consisting of different combinations of metal, metal oxide,...

The treatment of early-onset scoliosis (EOS) remains one of the biggest challenges in paediatric orthopaedics. Magnetically controlled growing rods (MCGRs) have increased in popularity compared to traditional growing rods (TGRs), providing curve correction, spinal growth and a reduction of the associated surgical trauma. Between May 2015 and July 2...

Forming industry is confronted with ever increasing demands on productivity, quality and performance of tools and dies. The main limiting factors are wear and fatigue resistance. Good abrasive wear resistance is obtained by increasing material hardness, which however may hamper toughness and fatigue resistance. Therefore different surface engineeri...

This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and ag...

This work explores the possibility of depth profiling of inorganic materials with Megaelectron Volt Secondary Ion Mass Spectrometry using low energy primary ions (LE MeV SIMS), specifically 555 keV Cu ²⁺ , while etching the surface with 1 keV Ar ⁺ ions. This is demonstrated on a dual-layer sample consisting of 50 nm Cr layer deposited on 150 nm In...

The influence of the flooding gas during ToF-SIMS depth profiling was studied to reduce the matrix effect and improve the quality of the depth profiles. The profiles were measured on three multilayered samples prepared by PVD. They were composed of metal, metal oxide, and alloy layers. Thickness of the layers for different samples was between 3 and...

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a very versatile surface-sensitive mass spectrometry method regarding the type of data that can be acquired. Measuring mass survey spectra, we analyse the sample surface and determine different ions through their m/z values as well as their intensities. SIMS depth profiles offer us the po...

Nanoporous ceramic coatings such as titania are promoted to produce drug-free cardiovascular stents with a low risk of in-stent restenosis (ISR) because of their selectivity towards vascular cell proliferation. The brittle coatings applied on stents are prone to cracking because they are subjected to plastic deformation during implantation. This st...

Natural clinoptilolite (CLI) exhibited a high efficacy in ciprofloxacin (CIP) removal from aqueous solution by adsorption. However, the regeneration of the spent adsorbent was a challenge since the adsorption occurred via electrostatic interactions and ion-exchange reaction. Herein, the feasibility of non-thermal plasma (NTP) was studied for the re...

Human hair absorbs numerous biomolecules from the body during its growth. This can act as a fingerprint to determine substance intake of an individual, which can be useful in forensic studies. The cocaine concentration profile along the growth axis of hair indicates the time evolution of the metabolic incorporation of cocaine usage. It could be eit...

V2O5–WO3, supported on TiO2 catalyst, was tested for n-butane oxidative dehydrogenation with NO/O2. The effect of physical oxygen mobility and nature in the V2O5–WO3/TiO2 catalyst on applicative catalytic performance was investigated. The influence of the O2/NO species on chemical reaction products/Mars–van Krevelen (MvK) cycle was examined by doin...

Transformation of tannic acid (TA), a cheap, abundant and environmentally friendly (by)product, upon carbonization at various temperatures was examined as it is extensively being used in energy storing devices. In addition of reviling what is happening with TA upon carbonization, a step further has been taken to scrutinize the role of carbonized TA...

The measured Auger electron spectroscopy (AES) depth profiles of the as-deposited Ag/Ni multilayers demonstrate a strong preferential sputtering effect. In the framework of the Mixing-Roughness-Information depth (MRI) model, the influence of preferential sputtering on the “measured” depth profile is quantitatively evaluated. The mass conservation u...

Energy-efficient photocatalytic CO2 reduction (PCO2R) into sustainable solar fuels is a highly enticing challenge for simultaneous settling of energy and environmental issues. Herein, we illustrate the synthesis and photocatalytic performance of a judiciously designed plasmonic Au nanoparticles photodeposited on TiO2-decorated N-doped graphene (ANG...

Stable chitosan thin films can be promising substrates for creating nanometric peptide-bound polyglucosamine layers. Those are of scientific interest since they can have certain structural similarities to bacterial peptidoglycans. Such films were deposited by spin coating from chitosan solutions and modified by acetylation and N-protected amino aci...

The selection of the wood surface pre-treatment process prior to finishing for an optimal wood-coating relationship can be challenging, but has a great significance for the properties of the coated products. The present study compares the surface properties of beech (Fagus sylvatica L.) wood after mechanical (MT), physical (PT) and chemical (CT) tr...

The influence of the flooding gas during ToF-SIMS depth profiling was studied to reduce the matrix effect and improve the quality of the depth profiles. The profiles were measured on three multilayered samples prepared by PVD. They were composed of metal, metal oxide, and alloy layers. Dual-beam depth profiling was performed with 1 keV Cs⁺ and 1 ke...

Potential induced degradation (PID) is a solar cell related degradation mechanism due to high potential difference in a photovoltaic (PV) module between the solar cells and its grounded frame. This type of degradation is well known for silicon PV, however, for perovskites it has not been thoroughly researched yet. Here, we investigate the PID of pe...

Composites of TiO2 and different amounts of plasmonic noble metal Au (0.25-2 wt.%) were synthesized by employing the wet impregnation technique. The results of SEM, TEM, XRD and N2 physisorption analyses reveal that the morphologies of the prepared composites are similar to the morphology of bare TiO2 support and are not influenced by the increasin...

Thin polymer films were deposited on polished stainless-steel samples by PECVD from a cyclopropylamine precursor and characterized by X-ray photoelectron spectroscopy, secondary-ion mass spectrometry and glow-discharge optical emission spectroscopy (GDOES) depth profiling. These depth profiles exhibited reasonable agreement. The GDOES involved the...

Laser texturing is a process that alters a material’s surface properties by modifying its morphology, which can improve properties like adherence, wettability, thermal and electrical conductivity and friction. Here, the effect of laser texturing was studied on an alpha-beta titanium alloy (Ti6Al4V) biomedical material. Two types of patterned surfac...

Nanostructured Fe2TiO5 (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe2TiO5 with high crystallinity and a large specific surface area. Herein, Fe2TiO5 nanofibers were sy...

The influence of the flooding gas and water during the ToF-SIMS depth profiling was studied in order to reduce the matrix effect and improve the quality of depth profiles. ToF-SIMS depth profiles were measured on three multilayered samples prepared by PVD deposition and on the PET foil. Multilayered samples were composed of metal, metal oxide and a...

Layer-by-layer bioactive coatings on AISI 316LVM and Ti90Al6V4 alloy were developed, showing great promise for biomedicine, especially as part of implantable metal-based composites. A corrosion study of the coated and uncoated samples was performed using electrochemistry. It was proven that such coatings do not increase the corrosion susceptibility...

Styrene is a widely used monomer in polymer industries for the manufacturing of plastics, rubbers and resins. The commercial styrene production process suffers from disadvantages such as requiring multiple steps, catalyst deactivation, high energy consumption and low yield. To address the aforementioned problems, metal complex catalysed single-step...

Nanocrystalline nickel manganite (NiMn2O4) powder with a pure cubic spinel phase structure was synthesized via sol-gel combustion and characterized with XRD, FT-IR, XPS and SEM. The powder was mixed with sodium alginate gel to form a nano-biocomposite gel, dried at room temperature to form a thick film and characterized with FT-IR and SEM. DC resis...